After cables using oil-impregnated paper as insulation have been terminated or spliced to other cables, the termination or splice area is conventionally insulated by filling it with a viscous liquid insulation. The flow properties of such an insulation permit it to serve as a reservoir, replenishing oil that drains into the cable, and taking up temperature-induced pressure changes that occur within the cable due to heating of conductors or cycling of ambient temperatures.
An important disadvantage of materials previously used as such a viscous liquid insulation, especially the commonly used highly viscous hydrocarbon-based compounds, is a requirement that they be heated to a low-viscosity condition to permit pouring them into an insulation housing, such as a termination bushing or splice casing, without entrapping air. Such heating operations, in which the compounds are heated to temperatures of 80.degree.-150.degree. C or more, are cumbersome and require extra equipment, fuel, and time to perform; they are hazardous to workmen, especially when the operation is performed at the top of a utility pole; and they may result in damage to adjacent equipment.
Another disadvantage with these high-viscosity compounds is that after installation they are quite stiff at normal ambient temperatures. Whenever it is desired to re-enter the termination or splice to change connections or to make a new connection, special tools must be used to strip away the insulation, and/or the compound must be heated to reduce its viscosity.
Lower-viscosity insulating materials have also been used, but they exhibit a different problem. Because of their low viscosity, they tend to drain excessively into the cable. Periodically they must be replenished, and crews regularly travel to the site of installation and repeat the pouring of insulation.
The result is that a need exists for an insulating material for terminations or splices of paper-insulated cables that will offer both a convenient installation procedure and desired properties after installation. Insofar as known, that need has never been met until the present invention.